Time delay relay



1943. o. w. LIVINGSTON 2,337,905

T IME DELAY RELAY Filed July 23, 1941 v Inventor: Orrin W [Livin ston b j a/wy'. 1 w

y His Attorney.

Patented Dec. 28, 1943 TIME DELAY RELAY .Orrin W. Livingston, Scotia, N. Y., assignor to General Electric Com New York pany, a corporation of Application July 23, 1941, Ser ial No. 403,612 12 Claims. 250-27) delay circuit or an electric valve time delay re- My invention relates to electric valve time delay circuits, or time delay relays, in which an electric discharge device and associated equipment are provided for obtaining a precise timing interval.

Electric valve equipment has been employed for obtaining precise and definite time intervals and has found considerable application in those fields where it is desired to effect energization or de-energization of an associated load circuit, or an electrical device, apredetermined interval of time after the occurrence of a circuit controlling operation. In accordance with the teachings of my invention described hereinafter, I provide a new and improved electric valve timing circuit, or time delay relay, which is susceptible of greater speed of operation between the timing intervals than that afforded by prior art arrangements. 1

It is an object of my invention to provide a new and improved electric timing circuit.

It is another object of my invention to provide a new and improved electric valve time delay relay.

It is a further object of my invention to pro.-

vide a new and improved electric valve system operation.

Briefly stated, in the illustrated embodiment of my invention I provide an electric valve timing circuit, or an electric valve time delay relay, which eil'ects energization or de-energization of an associated circuit a predetermined interval of time after the operation of an associated circuit controlling means, such as a switch. I provide a means for accelerating the operation of the relay so that it may be reset between timing intervals in a more rapid manner than that provided heretofore.

For a better understandingof my invention, reference may be had to the following description, taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. The single figure of the accompanying drawing diagrammatically illus trates an embodiment of-rny invention as applied to an arrangement for effecting energize.- tlon of an associated circuit, or load device, a predetermined interval of time after the operation of an associated control switch.

In the single figure of the drawing there is diagrammatically illustrated an embodiment of my invention as applied to an electric valve time by opening this switch.

lay, which may be energized from an alternating current supply circuit, such as a source of alternating voltage comprising conductors I and 2. The time delay relay comprises an electric discharge device 3 which may be of the type employing an ionizable medium and comprising an anode 4, a cathode 5, and a control member such as a control grid 6. If desired, the elec tric discharge device may also be provided with a an additional control member 1 which may be connected to the cathode 5. The anode-cathode circuit of the electric discharge device 3 may be connected to a load circuit, or a load device, such as a relay 8 comprising an actuating coil 9 and including contacts III which may be connected to control the energization of an associated circuit ll. v

I provide a suitable circuit controlling means, such as a switch l2, which is connected to the cathode of the electric discharge device 3 and to one terminal of the alternating current source, such as conductor 2. As will be apparent in view of the description appearing hereinafter, the timing operation of the relay in initiated by closure of the switch l2 and the relay is reset I. also provide across the source of alternating voltage a voltage divider I3 which may include resistances I4, l5 and it, one of which, such as resistance l5, being provided with an adjustable contact IS. The position of the adjustable contact i5 determines th timing interval of the relay. As the contact I5 is moved upward alon the resistance IS, the period of time delay is reduced and attains a minimum value in the uppermost position, Conversely, as the adjustable contact l5 in moved downward, the period oi time delay is increased and attains a maximum.

value in the lowermost position.

As an energy storage means for providing a negative potential which is impressed on grid 6 of electric discharge device 3 for maintaining this discharge device nonconducting for a predetermined interval of time after the closure of switch I 2, I provide a capacitance I"! connected between the intermediate point of the voltage divider i3, as indicated on the drawing, and the grid 6. A discharge path including a resistance I8 is connected across the capacitance l1.

To provide a path for the charging of the capacitance I! from the alternating current source during the time when the switch i2 is l the open circuit position, I provide an electri path which may include an impedance element,

\ itance I1 and grid 8.

such as a resistance I9, which is connected preterably between th cathode II and a point of the voltage divider I3 opposite the contact I5, as viewed from the cathode connection of the electric discharge device 3. In the particular embodiment of the invention illustrated, the resistance I9 is shown as being connected to the uppermost terminal of voltage divider I3. It is to be understood that the resistance I9 may be connected at any point along the resistance l4, or to any point of resistance I5 lying above the position of contact I5. When the switch I2 is open, the timing capacitance I1 is charged to the polarity indicated through a circuit including the cathode-grid circuit of electric discharge device 3. As will be appreciated, the rate at which the capacitance I1 is charged depends in a measure on the impedance of the cathode-grid circuit of the electric discharge device 3.

In order to increase the rate at which the capacitance I I is charged after opening switch I2 and, hence, as a means for increasing the reset speed of the relay, I provide an additional charg-' ing path 20 which is preferably connected to the cathode 5 and the common juncture of capac- The charging circuit 20 preferably includes a unidirectional conducting means, such as an electric valve 2|, poled to establish a negative charge on the right-hand plate of capacitance II when-the switch I2 is open. The unidirectional conducting means is preferably arranged to offer a substantially lower impedance than the cathode-grid impedance of the electric discharge device 3. That is, the unidirectional conducting means offers a substantially lower impedance to the flow of current than that ofl'ered by the cathode-grid circuit to the flow of grid-rectification current. In this manner, the reset speed of the relay is substantially increased, thereby increasing the field of application of the time delay relay.

The operation of the embodiment of my invention shown in the single figure oi the drawing will be explained by considering the system when it is desired to effect operation of relay 8 a predetermined interval of time after the closure of the control switch I2. Prior to closure of switch I2, thecapacitance I1 is charged to the polarity indicated during the half cycles 01 voltage of the alternating current source when the conductor 2 is positive in potential relative to conductor I through a circuit including resistance IS, the lower portion of resistance I5, capacitance II, the cathode-grid circuit of electric discharge device 3, and resistance IS. A portion of the negative charge of the capacitance I1 is accumulated on the plates of capacitance I I by virtue of the grid rectification current which the time when the switch I2 is open. It will be noted that the electric valve 2| is poled to establish a charge on the capacitance ll of the same polarity as that provided by the portion of the circuit including the cathode-grid circuit.

Upon closing switch I2, the electric discharge device 3 will not conduct current for a predetermined interval of time established by the constants of. the circuit. The length or duration of the minimum and maximum time delay intervals depends upon a number of factors, the principal ones being the value of the capacitance I1 and the value of resistance I 8. The minimum time delay also depends upon the value of resistance I4 and resistance I5. The electric discharge device 3 is maintained nonconducting for a pre determined interval of time due to the negative voltage impressed on grid 6 by virtue of the charge of capacitance II. There are two components of voltage impressed on grid 6 of the electric discharge device; one of these components is the alternating voltage derived from conductor 2 and the adjustable contact I5 of resistance I5. This component of voltage is derived from the source through resistance I4, the

upper portion of resistance I5, capacitance II,

unidirectional component provided by the precharge of capacitance I'I predominates and therefore maintains the electric discharge device 3 nonconducting. The negative unidirectional component of voltage produced by capacitance I'I immediately begins to decrease in magnitude upon closure of switch I2 because capacitance I'I discharges through resistance I8. After a predetermined interval of time, the grid 6 becomes sufiiciently positive with respect to the critical control characteristic oi the discharge device 3 and the device conducts current due to the establishment of the arc discharge between the cathode 3 and the anode 4. As soon as the electric discharge device 3 begins to conduct current, the load device or relay 8 will be energized eficcting operation thereof and controlling the circuit II a predetermined interval of time after the closure of switch I2.

The relay is reset by opening switch I2. The capacitance I I is charged to the polarity indicated during the half cycles of voltage of the source when conductor 2 is positive in potential relative to conductor I. which the capacitance I1 is charged during the reset period includes resistance iii, the lower portion of resistance I5, capacitance II, the gridcathode circuit of electric discharge device 3, and resistance I 9. An additional charging circuit including the electric path 20 and electric valve 2| also operates in parallel with the gridcathode circuit of electric discharge device 3 to irfcrease the rate at which the capacitance I1 is charged. By employing the additional circuit 20to expedite the establishment of a negative charge on the right-hand portion of capacitance II, it will be appreciated that I provide a highly satisfactory arrangement for decreasing the reset time of the relay. This increased speed is of considerable importance in those applications where it is required'to initiate the timing operations in rapid succession. Accordingly, it is of appreciable value to employ a time delay relay which requires a relatively short reset time.

While I have shown and described my invention as applied to a particular system of connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall The circuit through within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A time delay relay comprising a voltage divider arranged to be connected across a source of alternating voltage, a grid controlled electric discharge device having its anode and cathode connected to be supplied from said source, a

switch in the cathode connection, a capacitance connected between the grid and an intermediate point of said voltage divider, a resistance connected-between said cathode and said voltage divider at a point thereof on the opposite side of said capacitance connection relative to said first mentioned cathode connection, and a charging circuit for said capacitance connected between said cathode and the common juncture of said capacitance and said grid.

2. A time delay relay for controlling the energization of a load circuit from a source of alternating voltage and including an electric discharge device having an anode, a cathode and a grid, a voltage divider connected across said source, a capacitance connected between an intermediate point of said voltage divider and said grid, a

switch connected between said cathode and one terminal of said source, an impedance element connected between said cathode and a point of said voltage divider between said intermediate point and the other terminal of said source, and a unidirectional conducting device connected between said cathode and the common juncture of said capacitance and said grid.

3. A time delay relay for controlling the energization of a load circuit from a source of alternating voltage and including an electric discharge device having an anode, a cathode and a grid, a voltage divider connected across said source, a capacitance connected between said intermediate point of said voltage divider and said grid, a discharge circuit for said capacitance, a switch connected between said cathode and one terminal of said source, a resistance connected between said cathode and a point of said voltage divider opposite the cathode connection, and a unidirectional conducting device connected between said capacitance and said cathode for establishing a negative charge on said capacitance.

4. A time delay relay arranged to be connected across a source of alternating voltage including an electric discharge device having an anode, a cathode and a grid, the anode-cathode circuit being connected to be energized from said source, a voltage divider connected across said source, a switch in the cathode connection of said discharge device to said source, a timing capacitance connected between an intermediate point of said voltage divider and said grid, a conductive path from said cathode to one terminal of said source to establish a circuit for charging said capacitance through the grid-cathode circuit of said electric discharge device, and a unidirectional conducting device connected between said cathode and the common juncture of said capacitance and said grid to provide an additional path for increasing the rate at which said capacitance is charged.

5. A time delay relay for controlling the energization of a load circuit from a source of alternating voltage including an electric discharge device having an anode, a cathode and a grid,

the anode-cathode circuit oi. the electric discharge device being connected to be energized from said source, a voltage divider connected across said source, a capacitance connected between on intermediate'pointoi said voltage divider and said grid, a switch connected between the cathode and said source, an impedance element connected between said cathode and said source to establish a path for the charging of said capacitance to impress negative voltage on said grid when said switch is in the open circuit I position, and a unidirectional conducting device connected between said cathode and the common juncture of said. capacitance and said grid.

6. A time delay relay comprising a voltage divider arranged to be connected across a source of alternating voltage, an electric discharge device having its anode and cathode connected to be supplied from said source, a switch in the cathode connection of said discharge device to said source, a capacitance connected between the grid and an intermediate point of said voltage divider, a reactance connected between said cathode and a point 01' said voltage divider on the opposite side of the capacitance connection relative to the cathode connection for providing a path for charging said capacitance through the cathodegrid circuit of said electric discharge device to impress a negative voltage on said grid, and an additional charging circuit for said capacitance comprising a unidirectional conducting device connected between said cathode and the common juncture of-said capacitance and said grid.

7. In combination, a source of alternating voltage, a load device, a time delay relay for effecting v energization of said load device a predetermined interval oi! time after a controlling operation comprising an electric discharge device having an anode, a cathode and a grid, the anode-cathode circuit being connected to said load device and to said source, a voltage divider connected across said source, a capacitance connected between an intermediate connection of said voltage divider and said grid, a switch connected between said cathode and said source, a resistance connected between said cathode and one terminal of said source to provide a conducting path for the charging of said capacitance through the cathode-grid circuit of said electric discharge device when said switch is in the open circuit position, and an additional electric path for charging said capacitance comprising a unidirectional conducting device connected between said cathode and the common juncture of said capacitance and said grid.

8. A time delay relay comprising a voltage divider arranged to be connected across a source of alternating voltage, a grid controlled electric discharge device having its anode and cathode connected to be supplied from said source, a switch in the cathode connection, a capacitance connected between the grid and an intermediate point of said voltage divider, a resistance connected between said cathode and said voltage divider at apoint thereof on the opposite side of said capacitance relative to the cathode connection, and a unidirectional conducting device connected in circuit with said capacitance for providing an additional path for accelerating the charging of said capacitance when said switch is in the open circuit position.

9. A time delay relay connected to be operated from a source of alternating voltage including an electric discharge device having an anode, a oath ode and a grid, a capacitance, means for charging said capacitance to impress a negative unidirectional biasing potential on said grid to maintain said discharge device nonconducting for a pro- I tance of the same polarity as that the grid rectification current.

determined interval oi time and comprising a circuit including the grid-cathode circuit of said electric discharge device and a unidirectional conducting device connected to operate in parallel with the grid-cathode circuit of said electric discharge device for establishing a charge on said capacitance of the same polarity as that produced/ by the grid rectification current of said electric discharge device. 10. A time delay relay connected to be energized from a source of alternating voltage including an electric discharge device having an anode, a cathode and a grid, means including a capacitance tor impressing on said grid 9. negative unidirectional biasing potential sumcient to maintain said discharge device nonconducting for a predetermined interval or time, means including the grid-cathode circuit of. said electric discharge device for charging said capacitance by utilizing the grid rectification current of said discharge device, and means connected between said grid and said cathode for establishing a charge on said capaci- 11. A time delay relay connected to be energized irom'a source oialtemating voltage including anelectric discharge device having an anode, a cathode and a grid, means including a capacitance for-impressing on said grid a biasing potential suiilcient to maintain said electric discharge devic in a predetermined condition of conducproduced by memos including the grid-cathode circuit of said electric discharge device for charging said capacitance by utilizing the grid rectification current or said discharge device, and means including a unidirectional conducting device for establishing a charge on said capacitance of the same polarity as that produced by the grid rectification current to decrease the reset time required to restore said biasing potential on said capacitance.

12. A time delay relay connected to be energized from asource 01' current including an electric discharge device having an anode, a cathode and a grid, means including a capacitance for impressing on said grid a biasing potential suincient to maintain said electric discharge device in a predetermined condition of conductivity for a predetermined interval of time, means including the grid-cathode circuit of said electric discharge device for charging said capacitance by utilizing the grid-rectification current oi. said discharge device, and mean including a unidirectional conducting device having an impedance substantially smaller than that or the grid-cathode circuit or said electric discharge device for establishing a charge on said capacitance of the same polarity as that produced by the grid-rectiflcation current to decrease the reset time required to restore said biasing potential on said capacitance. ORRIN W; LIVINGSTON.'

tivity for a predetermined interval or time, means 

